Check the following box to designate the rule pursuant to which
the Schedule is filed:

¨

Rule 13d-1(b)

x

Rule 13d-1(c)

¨

Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing
information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall
not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or
otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however,
see the Notes).

D. E. Shaw & Co., L.P. is a limited partnership organized under the laws of the state of Delaware.

David E. Shaw is a citizen of the United States of America.

(d)

Title of Class of Securities

Common Stock, $0.01 par value

(e)

CUSIP Number

29264F205

Item 3.

If this statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) or (c), check whether the person filing is a:

Not Applicable

Item 4.

Ownership

As of June 1, 2012:

(a)

Amount beneficially owned:

D. E. Shaw & Co., L.P.:

5,869,712 shares

This is composed of (i) 5,444,773 shares in the name of D. E. Shaw
Valence Portfolios, L.L.C., which includes exposure to shares through derivative instruments, (ii) 331,667 shares in the name of
D. E. Shaw Oculus Portfolios, L.L.C., (iii) 93,231 shares in the name of D. E. Shaw Heliant Portfolios, L.L.C., and (iv)
41 shares in the name of D. E. Shaw Asymptote Portfolios, L.L.C.

David E. Shaw:

5,869,712 shares

This is composed of (i) 5,444,773 shares in the name of D. E. Shaw
Valence Portfolios, L.L.C., which includes exposure to shares through derivative instruments, (ii) 331,667 shares in the name of
D. E. Shaw Oculus Portfolios, L.L.C., (iii) 93,231 shares in the name of D. E. Shaw Heliant Portfolios, L.L.C., and (iv)
41 shares in the name of D. E. Shaw Asymptote Portfolios, L.L.C.

(b)

Percent of class:

D. E. Shaw & Co., L.P.:

5.0%

David E. Shaw:

5.0%

(c)

Number of shares to which the person has:

(i)

Sole power to vote or to direct the vote:

D. E. Shaw & Co., L.P.:

-0- shares

David E. Shaw:

-0- shares

(ii)

Shared power to vote or to direct the vote:

D. E. Shaw & Co., L.P.:

5,869,712 shares

David E. Shaw:

5,869,712 shares

(iii)

Sole power to dispose or to direct the disposition of:

D. E. Shaw & Co., L.P.:

-0- shares

David E. Shaw:

-0- shares

(iv)

Shared power to dispose or to direct the disposition of:

D. E. Shaw & Co., L.P.:

5,869,712 shares

David E. Shaw:

5,869,712 shares

David E. Shaw does not own any shares directly. By virtue of
David E. Shaw’s position as President and sole shareholder of D. E. Shaw & Co., Inc., which is the general partner of
D. E. Shaw & Co., L.P., which in turn is the manager and investment adviser of D. E. Shaw Valence Portfolios, L.L.C.,
the investment adviser of D. E. Shaw Oculus Portfolios, L.L.C., and the managing member of (i) D. E. Shaw Heliant Adviser,
L.L.C., which in turn is the investment adviser of D. E. Shaw Heliant Portfolios, L.L.C., and (ii) D. E. Shaw Adviser, L.L.C.,
which in turn is the investment adviser of D. E. Shaw Asymptote Portfolios, L.L.C., and by virtue of David E. Shaw’s
position as President and sole shareholder of D. E. Shaw & Co. II, Inc., which is the managing member of D. E. Shaw
& Co., L.L.C., which in turn is the manager of D. E. Shaw Oculus Portfolios, L.L.C. and the managing member of (i)
D. E. Shaw Heliant Manager, L.L.C., which in turn is the manager of D. E. Shaw Heliant Portfolios, L.L.C., and (ii) D. E. Shaw Manager, L.L.C., which in turn is the manager D. E. Shaw Asymptote Portfolios, L.L.C., David E. Shaw may be deemed to have
the shared power to vote or direct the vote of, and the shared power to dispose or direct the disposition of, the 5,869,712 shares
as described above constituting 5.0% of the outstanding shares and, therefore, David E. Shaw may be deemed to be the beneficial
owner of such shares. David E. Shaw disclaims beneficial ownership of such 5,869,712 shares.

Item 5.

Ownership of Five Percent or Less of a Class

Not Applicable

Item 6.

Ownership of More than Five Percent on Behalf of Another Person.

Not Applicable

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person.

Not Applicable

Item 8.

Identification and Classification of Members of the Group

Not Applicable

Item 9.

Notice of Dissolution of Group

Not Applicable

Item 10.

Certification

By signing below, each of D. E. Shaw & Co., L.P. and
David E. Shaw certify that, to the best of such reporting person’s knowledge and belief, the securities referred to above
were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of
the securities and were not acquired and are not held in connection with or as a participant in any transaction having such purposes
or effect.

SIGNATURE

After reasonable inquiry and to the best of their knowledge
and belief, the undersigned certify that the information set forth in this statement is true, complete and correct. A Power of
Attorney, dated December 15, 2011, granted by David E. Shaw in favor of Nathan Thomas, is attached hereto.